First of all, I tried using the promotions tab on my facebook business page to run the raffle I was using woobox to manage. The interface was horrible. When I clicked the raffle link, it brought me to a mostly blank promotions page with a small link in the corner that you had to click to see the full raffle page. I'm sure this was confusing for whoever tried to click the link, plus involved an extra click. I probably lost a good deal of leads this way, but had already paid for the service (you will have to pay to officially start your campaign) and was financially committed.
Second, when running a facebook campaign using woobox they give you the ability to launch a facebook ad from within woobox. While this sounds like a great feature. You are very limited in your control of the audience that sees the ad and other ad features. You then have to go into facebook ad manager to further refine your ad audience, etc... so what's the point of even providing this feature?
Third, the raffle manager is a little clunky and takes some getting used to.
Last, they have a NO REFUND policy so if you don't like the service, or forget to cancel you will not get your money back!
I think there are better services out there, including wishpond, which I recently used and worked much better.
Running a raffle contest to generate likes and engagement on facebook, building brand awareness, as well as generating web traffic and leads.